1. Field of the Invention
The present invention relates to an apparatus and a method for transmitting and receiving Caller ID (CID) in a network exchange.
2. Background of the Related Art
A network exchange (e.g., a Private Branch Exchange (PBX) for transmitting/receiving CID of the related art is explained with reference to drawings. Before getting into further description, it will be helpful to explain about CID service. As the name implies, CID service provides a caller's phone number on a receiver's phone or display terminal before the receiver answers the call.
FIG. 1 is a schematic block diagram of a configuration of an apparatus for transmitting and receiving CID in PBX of the related art. FIG. 2 is a schematic block diagram of a configuration of an analog trunk convergency illustrated in FIG. 1. FIG. 3 is a schematic block diagram of a configuration of a subscriber line convergency illustrated in FIG. 1.
Referring to FIG. 1, the PBX 110 receives a CID provided through an office line from a public exchange (PX) 100 and transmits the CID to an affected terminal. The PBX 110 for CID service includes an Analog Trunk Convergency or interface (ATC) block 120, a system control block 125, a system bus control block 130, a switching block 135, a DTMF transmitting/detecting block 140, and a Subscriber Line Convergency or interface (SLC) block 150.
The ATC block 120 is used for converging with lines connected to an external exchange (for example, a payphone). Thus, when a ring signal is received from the public exchange 100, the ATC block 120 detects the ring signal and obtains a CID provided between the first ring signal and the second ring signal and stores the CID in a predetermined area of each port.
Additional details on the ATC block 120 follow with reference to FIG. 2. As shown in the drawing, the ATC block 120 includes a plurality of ports (e.g., 32 ports) 111, a local control block 117, a memory interface block 118, and memory blocks 119 for respective ports. Each of the plurality of ports 111 detects a ring signal that is transmitted through an office line, transmits the ring signal detection data to the local control block 117, and detects the CID utilizing the ring signal.
Each of the plurality of ports 111 includes an A/D and D/A converting block 112 for converting the CID received from the public exchange 100 through a subscriber line into analog data and transmitting the data to the switching block 135 through a highway, one of data paths, a ring detecting block 113 for detecting a ring signal received from the public exchange through the subscriber line, a holding line 114 for establishing and holding a line, and a CID detecting block 115 for detecting the CID received between the first ring and the second ring.
The CID, being detected by the CID detecting block 115, is then transmitted to the port memory blocks 119 through the memory interface block 118. The memory blocks 119 store the CID in the predetermined areas of respective ports. The local control block 117 reads the ring signal detection data provided by the ring detecting block 113 and the CID stored in the memory blocks 119, and transmits them to the system control block 125 through the system bus.
As shown in FIG. 3, the SLC block 150 includes a local control block 157, a memory block 159, a memory interface block 158, and a plurality of ports 151. The local control block 157 transmits a ring transmission message to each of the ports 151, receives the CID from the system control block 125, and transmits the CID to the memory 159. The memory block 159 stores the CID provided by the local control block 157 in a corresponding area of each port.
Each of the ports 151 includes an A/D and D/A converting block 152 for converting digital data transmitted through the system bus into analog data and transmitting the converted data to an affected receiver terminal, a ring transmitting block 153 for transmitting a ring, corresponding to the ring transmission message that is transmitted to the local control block 157 through the system bus, a CID transmitting block 155 for extracting the CID between the first ring and the second ring from the port memory blocks 159 when the ring is transmitted, and transmitting the CID to an affected terminal, and a system tone transmitting block 156 for extracting and transmitting a system tone, and an off-hook detecting block 154 for detecting off-hook status of the affected terminal of a receiver.
Referring back to FIG. 1, operation principles of receiving the CID in the PBX of the related art are now explained. The system control block 125 transmits the ring transmission message to the SLC block 150, in response to the ring signal detection data transmitted from the ATC block 120. Also, the system control block 125 transmits the CID transmitted from the ATC block 120 to the affected SLC block 150 through the system bus. Then the SLC block 150 transmits the CID, which has been transmitted through the system bus, to a CID phone 160 of a corresponding port.
Following is a description of a method for receiving the CID in the PBX of the above construction. When a ring tone is received to the ATC block 120 in the PBX 110 from the SLC block 150 in the PX 100, the ring detecting block 113 in the ATC block of FIG. 2 detects whether the ring tone has actually been received, and if so, the local control block 117 reports it to the system control block 125 through the system bus. In general, the CID is received between the first predetermined ring and the second predetermined ring. Here, the CID detecting block 115 stores, through the memory interface block 118, the CID in the predetermined areas of the port memory blocks 119. The local control block 117 reads the CID being stored in each of the port memory blocks, and reports it to the system control block 125 through the system bus. The system control block 125 transmits the CID to the corresponding SLC block 150 in the PBX 110 through the system bus.
Later, the local control block 157 in the SLC block 150 provides the CID service to each of the affected ports 151. Then the CID is transferred through the subscriber line and displayed on the caller ID phone 160 at the subscriber side. To transmit and receive the CID, a commercialized IC has been traditionally used as a line base as illustrated in FIGS. 2 and 3. As a result, the CID display in the PBX of the related art has been ineffective and uneconomical.